JPH1048675A - Variable color filter - Google Patents

Abstract

(57) [Summary] [Purpose] The manufacturing cost can be reduced.
It is an object of the present invention to provide a color variable color filter capable of realizing an LCD with high image quality and sufficient brightness. A pair of transparent electrodes 2-1 and 2-2 are attached to a filter body 1 in which a PLZT layer 10 and a ZnO layer 11 are laminated, and a voltage supply unit 3 is attached to the pair of transparent electrodes 2-1 and 2-2. Connecting. Thereby, when the voltage is not supplied from the voltage supply unit 3 to the pair of transparent electrodes 2-1 and 2-2, the filter body 1 filters the blue light B, turns on the switch 32, and turns on the power supply 30. When the voltage of is supplied, the filter body 1 filters the green light,
When the switch 33 is turned on and the voltage of the power supply 31 is supplied, the filter body 1 filters the red light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference type color filter used for selecting colors of an LCD (Liquid Crystal Display), and more particularly to a color variable color filter capable of performing color modulation by voltage control.

[0002]

2. Description of the Related Art A color filter is an important component of an LCD, and holds a key to high performance such as low cost and high speed response of the LCD. There are two types of color filters: absorption color filters and interference color filters.

[0003] Interference type color filters have the advantage of higher color characteristics and transmittance than absorption type color filters. As shown in FIG. 6, this interference type color filter has a structure in which thin films 9a having a high refractive index such as ZnS and thin films 9b having a low refractive index such as Na3AlF6 are alternately laminated with an optical thickness of 1/4 wavelength. The incident light repeats reflection and interference at the interface between the two types of thin films 9a and 9b, so that only light of a specific wavelength is enhanced and extracted to the outside. Therefore, in order to improve the filter characteristics, it is necessary to increase the number of thin films 9a and 9b to be laminated, and there are usually about 10 layers to several tens layers.

[0004]

However, the above-mentioned conventional color filters have the following problems. In a conventional interference type color filter, two layers 9a and 9b having different refractive indexes are separated by sputtering to 323.5 nm.
A portion for extracting red light (wavelength 647 nm) is manufactured by laminating at intervals, and a green light (wavelength 5
A portion for extracting blue light (wavelength: 456 nm) is manufactured by laminating a portion for extracting blue light (wavelength: 456 nm). Therefore, a complicated sputtering operation must be performed for each of the above-described parts, and the number of manufacturing steps is large. As a result, the cost of the product is high. Further, in a conventional color filter, one pixel is constituted by a portion for extracting red light, a portion for extracting green light, and a portion for extracting blue light. FIG. 7 is a schematic diagram showing one pixel of a conventional color filter.
(A) shows one pixel of a color filter in which a red light portion R1, a green light portion G1, and a blue light portion B1 are arranged in a sprite shape. In such a color filter, FIG.
(B) to (d), the red light portion R1 emits the red light R, the green light portion G1 emits the green light G, and the blue light portion B1.
To extract blue light B. Therefore, only one-third of one pixel is used to emit light. In an LCD using this color filter,
Low resolution and poor image quality. Furthermore, the brightness is not enough. Also, as shown in FIG. 8A, the red light portion R1
And a green light portion G1 and a blue light portion B1 are arranged in a delta shape to form one pixel. In this color filter as well, as shown in FIGS. 8B to 8D, The red light R is extracted from the red light portion R1, the green light G is extracted from the green light portion G1, and the blue light B is extracted from the blue light portion B1, which causes the same problem as described above.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and provides a color variable color filter capable of reducing the manufacturing cost and realizing an LCD having high image quality and sufficient brightness. It is intended to be.

[0006]

In order to solve the above-mentioned problems, a color variable color filter according to the first aspect of the present invention comprises:
A filter main body formed by alternately stacking a piezoelectric transparent first layer and a piezoelectric transparent second layer having a refractive index different from that of the first layer is sandwiched between the filter main body. And a voltage supply unit that supplies a voltage to the pair of transparent electrode units.

According to a second aspect of the present invention, in the color variable color filter according to the first aspect, the voltage supply unit causes each of the first and second layers to emit one-fourth of red light when applied. A first voltage that displaces to a thickness of a wavelength, a second voltage that displaces each of the first and second layers to a thickness of a quarter wavelength of green light when applied, And a third voltage for displacing each of the first and second layers to a thickness of a quarter wavelength of blue light can be selectively supplied.

According to the first aspect of the present invention, when a predetermined voltage is supplied from the voltage supply section to the pair of electrode sections, the predetermined voltage is applied to the filter body section sandwiched between the pair of transparent electrode sections. . As a result, the first and second piezoelectric layers are displaced in accordance with the voltage, and the thicknesses of these layers are changed. Therefore, if a voltage is supplied from the voltage supply unit such that the thickness of each of the first and second layers becomes ４ of the wavelength of the specific light, only the specific light is applied to the first and second layers. Reflection and interference are repeated at the interface of the layers, and are strengthened and taken out of the filter body.

According to the second aspect of the present invention, when the first voltage is applied from the voltage supply unit to the filter body, each of the first and second layers has a thickness of a quarter wavelength of blue light. Is displaced. Therefore, when white light is applied to the filter body, only blue light is extracted. And in the same way,
When the second voltage or the third voltage is applied to the filter body, only the green light or the blue light is extracted from the white light.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a color variable color filter according to an embodiment of the present invention. As shown in FIG. 1, the color variable color filter includes a filter main body 1, a pair of transparent electrodes 2-1, 2-2, and a voltage supply 3.

The filter body 1 has a structure in which a PLZT layer 10 (a layer made of (Pb, La) (Zr, Ti) O3) as a first layer and a ZnO layer 11 as a second layer are alternately laminated. It has become. Specifically, each PLZT layer 1
0 and the thickness of each ZnO layer 11 are set to 114 nm,
The PLZT layers 10 and the ZnO layers 11 are alternately laminated by 20 layers to form the filter body 1 having an overall thickness L of 4.56 μm. Further, each PLZT layer 10 and each ZnO layer 11 are formed of piezoelectric materials having different refractive indices, and have an average strain rate of 55 per 1 V applied voltage.
It is 0 × (10 minus the twelfth power) m. The filter main body 1 having such a structure can be manufactured by stacking the PLZT layer 10 and the ZnO layer 11 using a film forming process such as sputtering.

The pair of transparent electrodes 2-1 and 2-2 are made of ITO.
The transparent electrode is formed on both surfaces of the filter body 1 by a film forming process such as sputtering. The voltage supply unit 3 is connected to the pair of transparent electrodes 2-1 and 2-2.

The voltage supply unit 3 includes a pair of transparent electrodes 2-1 and 2-1.
This is a portion for supplying a voltage to 2-2, and has power supplies 30 and 31 connected in parallel. Power supply 30 is 230V DC
The positive electrode is connected to the transparent electrode 2-1 via the switch 32, and the negative electrode is connected to the transparent electrode 2-2. The power supply 31 is a constant voltage source of DC 760 V, and the positive electrode is connected to the transparent electrode 2-1 via the switch 33, and the negative electrode is connected to the transparent electrode 2-2. Therefore, as shown in FIG.
By turning off both 2 and 33, a voltage of 0 V as the first voltage is supplied to the pair of transparent electrodes 2-1 and 2-2. In addition, by turning on only the switch 32, a voltage of 230V as the second voltage is supplied to the pair of transparent electrodes 2-1 and 2-2, and by turning on only the switch 33, the second voltage is turned on. A voltage of 760 V as the voltage of 3 is supplied to the pair of transparent electrodes 2-1 and 2-2.

Next, the operation of the color variable color filter of this embodiment will be described. First, as shown in FIG. 1, when the switches 32 and 33 are both turned off and the voltage of the voltage supply unit 3 is not applied to the filter main unit 1, the filter main unit 1 maintains the initial state. The thickness L is maintained at 4.56 μm. Therefore, each PL
The thickness of the ZT layer 10 and each ZnO layer 11 is maintained at 114 nm, and the interlayer distance d is maintained at 228 nm. That is, the thickness of each PLZT layer 10 and each ZnO layer 11 is a quarter wavelength of the blue light B (wavelength 456 nm), and the interlayer distance d is a size of a half wavelength of the blue light B. Has become. Thus, when the filter body 1 is irradiated with white light W, only the blue light B is emitted from the PLZT layer 10 and the ZnO layer 11.
The light is repeatedly reflected and interfered at the interface with the filter body, and is strengthened and taken out of the filter main body 1.

As shown in FIG. 2, when only the switch 32 of the voltage supply unit 3 is turned on, a 230 V voltage from the power supply 30 is applied to the filter body 1. At this time, since the average strain rate of each PLZT layer 10 and each ZnO layer 11 is 550 × (10 −12) m per 1 V applied voltage, each PLZT layer 10 and each ZnO layer 11
O layer 11 is displaced to a thickness of approximately 128.5 nm. That is, the thickness of each PLZT layer 10 and each ZnO layer 11 is changed to a quarter wavelength of the green light G (wavelength 514 nm), and the interlayer distance d1 is substantially equal to a half wavelength of the green light G. It will be. As a result, the white light W passes through the filter body 1
, Only the green light G is taken out of the filter body 1.

Further, as shown in FIG.
When only the switch 33 is turned on, a voltage of 760 V from the power supply 31 is applied to the filter body 1, and each of the PLZT layers 10 and each of the ZnO layers 11 are substantially 161.75.
Displaced to a thickness of nm. That is, the thickness of each PLZT layer 10 and each ZnO layer 11 is the red light R (wavelength 647 nm).
And the interlayer distance d2 becomes substantially equal to the half wavelength of the red light R. Thus, when the white light W is applied to the filter body 1, only the red light R is extracted.

As described above, the color variable color filter according to the present embodiment functions as an interference type color filter capable of performing color modulation by turning on and off the switches 32 and 33 of the voltage supply unit 3. Therefore, as shown in FIG.
A pair of transparent electrodes 2-1 and 2-2 are arranged in a grid pattern on both sides of the filter main body 1, and the color variable color filter of the present embodiment is applied as an interference type color filter having an intersection portion as one pixel. Accordingly, one pixel can be used as a light emitting portion of the red light R, the green light G, and the blue light B, and as a result, the resolution of the LCD can be increased and the image quality can be improved. Further, the brightness of one pixel reaches three times the brightness of the conventional color filter shown in FIGS. Further, a pair of transparent electrodes 2-
Since the components 1-2 and the filter body 1 can be formed at once by a film forming process such as sputtering, the number of manufacturing steps can be reduced, and as a result,
Product cost can be reduced.

The present invention is not limited to the above embodiment, and various modifications and changes can be made within the scope of the invention. In the above embodiment, as the piezoelectric transparent first layer, (Pb, La) (Zr, Ti) O
3 is used as a piezoelectric transparent second layer having a different refractive index from the PLZT layer 10.
Although the ZnO layer 11 was used, the present invention is not limited to this. The first and second layers only need to be made of a piezoelectric transparent material and have different refractive indices. So, for example,
(Pb, Bi) (Zr, Ti) O3, (Pb, La)
(Hf, Ti) O3, (Pb, Ba) (Zr, Ti) O
3, (Pb, Sr) (Zr, Ti) O3, (Pb, La)
(Mg, Nb, Zr, Ti) O3, (Sr, Ca) (L
i, Nb) O3, (Sr, Ca) (Li, Nb, Ti)
Select two materials from O3, and with those materials,
A first layer and a second layer may be formed. In the above-described embodiment, three types of voltages are applied to the filter body 1 by switching the switches 32 and 33 of the voltage supply unit 3. However, for example, as shown in FIG. May be configured with one power supply 40 and a variable resistor 41, and by changing the resistance value of the variable resistor 41, the voltage from the power supply 40 may be changed in an analog manner and applied to the filter body 1. Thus, an interference type color filter capable of filtering light of various wavelengths can be realized.

[0019]

As described in detail above, according to the color variable color filter of the present invention, light of various wavelengths can be filtered only by changing the voltage applied from the voltage supply unit to the filter body. Therefore, one pixel can be used as a light emitting portion for red light, green light, and blue light. As a result, it is possible to increase the resolution of an image, to achieve high image quality and high quality of the LCD, and to increase the brightness of the LCD screen. Further, since the filter main body can be manufactured at once by a film forming process such as sputtering, the number of manufacturing steps can be reduced, and as a result, the cost of the product can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a color variable color filter according to an embodiment of the present invention, showing a state where no voltage is applied.

FIG. 2 is a switch state diagram when a 230V voltage is applied.

FIG. 3 is a switch state diagram when a 760V voltage is applied.

FIG. 4 is a plan view showing a pixel.

FIG. 5 is a circuit diagram showing a modification of the voltage supply unit.

FIG. 6 is a structural diagram of a conventional interference type color filter.

FIG. 7 is a schematic view showing an example of a pixel of a conventional color filter. FIG. 7A shows a red light portion R1 and a green light portion G.
7 shows one pixel of a color filter in which a blue light portion B1 is arranged in a sprite shape, and FIG.
FIG. 7C shows a light emission state of green light G, and FIG. 7D shows a light emission state of blue light B.

FIG. 8 is a schematic view showing another example of a pixel of a conventional color filter. FIG. 8A shows a color in which a red light portion R1, a green light portion G1, and a blue light portion B1 are arranged in a delta shape. FIG. 8B shows one pixel of the filter, and FIG.
8C shows a light emitting state of the green light G, and FIG. 8D shows a light emitting state of the blue light B.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Filter body part, 2-1 and 2-2 ... Transparent electrode, 3 ... Voltage supply part, 30, 31 ... Power supply, 32, 33 ... Switch, 10 ... PLZ
T layer, 11 ... ZnO layer, d, d1, d2 ...
Interlayer distance, L: Overall thickness.

Claims (2)

[Claims] A filter main body formed by alternately laminating a piezoelectric transparent first layer and a piezoelectric transparent second layer having a refractive index different from that of the first layer; A color variable color filter, comprising: a pair of transparent electrode portions provided so as to sandwich a main body portion; and a voltage supply portion for supplying a voltage to the pair of transparent electrode portions. 2. The color variable color filter according to claim 1, wherein the voltage supply unit causes each of the first and second layers to emit red light when applied.
A first voltage that is displaced to a thickness of one-quarter wavelength, and when applied, causes each of the first and second layers to occupy one quarter of green light
A second voltage for displacing to a thickness of a wavelength, and a third voltage for displacing each of the first and second layers to a thickness of a quarter wavelength of blue light when applied. A color variable color filter, which can be supplied to a color filter.